This is a study that will consider the effect that inaccurate statement of age on the death certificate and in the census record has on the published death rates for the very elderly, and in turn, on the life table values for this population. Particular emphasis will be given to examining differentials in accuracy by race and sex. By using a procedure known as the "method of extinct generations", a method that permits the recostruction of "extinct" population cohorts from the death statistics for a series of years, new estimates of the United States population 85 years of age and over will be prepared for the years 1951 through 1965 for single years of age by sex and race. In addition, estimates of the number of persons 90 years of age and over will be developed for the period from 1966 through 1970. The resulting estimates for the periods around 1950, 1960 and 1970 censuses will be compared with decennial census statistics. Consideration also will be given to the findings from the previous research matching age on the death certificate and on the 1960 census record. A series of age-specific death rates will be computed from the derived populations (deaths serving as both numerator and donominator) and these will be compared with official data for the United States published by the National Center for Heatlh Statistics. The new series of death rates will be utilized in the preparation of life tables for the elderly, and the values obtained will be compared with the official current United States life tables. They will also be compared with measures of longevity for older persons in European countries that have been derived in similar fashion. Trends in mortality and survival among the extreme aged population will be analyzed for the decades of the 1950s and 1960s using the data computed, which should provide a more accurate measure of the experience during this time period than previously available information.